Centrifugal compressor.



S. A. MOSS.

GENTRIFUGAL OUMPRESSOR.

APPLICATION FILED MAB. 5, 190a.

Patented Oct. 15, 1912.

2 SHEETS-SHEET 1.

Inventor: nford 0Q 055 S. A. MOSS.

GENTRIFUGAL COMPRESSOR.

APPLICATION FILED MAR. 5, 1908.

1,041,505., 1 I Patented 001. 15, 1912.

2 SHEETS-SHEET Z.

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5 E z 16 2 15 I4 I llll O 7 2'5 KSQ I Witnesses: Inventor:

' Sanford.|\/Ioss,-

UNITED STAEN SANFORD A. MOSS, OF LYNN, MASSACHUSETTS, ASS-IGNOR TOGENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL COMPRESSOR.

Specification of Letters Patent.

, Patented Oct. 15,i912.

Application filed March 5, 1908. Serial No. 419,278.

.Lynn, county of Essex, State of Massachusetts, haye invented certainnew and useful Improvements in- Centrifugal Compres= sors, of whichtheifollowingis a specification. I

When the ordinary "reciprocating compressor is employed to supply air toa blast furnace or cupola and a choke occurs some- Where in the airpassages which reduces the air openings, the pressure automaticallyincreases or buildsup until the choke is removed. This is due to thefact that the piston of the compressor displaces a given volume of air.on each stroke and is moving at constant speed. The centrifugalcompressor has many important advantages over the reciprocatingcompressor for such work but it has this objection, namely, that ifdriven at constant speed by a suitable prime mover it will givepractically constant pressure under all circumstances. In

other words, if the cupola chokes up, the

compressor will supply less air but at the same constant pressure,whereas as above pointed out, an increased pressure is necessary toovercome the choke or obstruction.

My invention has for its object the overcoming of the objection abovereferred to by so arranging, constructing and operating the apparatusthat .just as soon as the amount of air delivered by the centrifugalcompressor and consequently the load on the prime mover driving saidcompressor decreases owing to a'choke in the cupola or other apparatus,the speed of the compressor and of its driving motor will, because ofthe unchanged or constant supply of energy to the driving motor,automatically increase until the air pressure is increased suflicientlydue to said increase in speed to overcome the choke or obstruction,after which the pressure and speed will decrease and return to theirnormal conditions. Should a predetermined increase of pressure fail toremove the choke, provision is made for preventing further increase inspeed above a desired maximum by controlling the supply compressor.

pressure at said speed for all loads, that is for all quantities offluid discharged by the The compressor illustrated is designed to su ply7000 cubic feet of free air per second at a pressure of .88 pounds persquare inch under normal conditions. The quantity and pressure of theair or other elastic fluid delivered can be changed to meet difierentnormal conditions by suitably changing the parts and driving theimpeller ofthe compressor at the proper speed.

Mounted on the same shaft with the impeller of the compressor, or on adifferent shaft and connected thereto, is the moving element of adriving motor. As an illustration of amotor I have shown a steam turbinesiiice it'is particularly Well adapted for the purpose on account of itssimplicity,

economy of operation and relatively high speed, but the invention is notnecessarilyv limited thereto in all particulars.

The

turbine is provided with one or more'noz- -zles or other fluiddischarging devices to admit the required amount of steam to drive thebucket wheel and the impeller at such speed as will cause the latterunder normal conditions to deliver the'desired quantity of air at thepredetermined pressure. Theturbine is provided with a governor whichunder normal conditions of operation and V to the volume. Hence when thevolume decreases the pressure increases. To state the matter in anotherway, if the cupola chokes, the load on the compressor or in other words,the quantity of air delivered by the compressor, decreases while thespeed of its lmpeller increases because the input. of energy in the formof steam supplied to the turbine remains the same and the load on theturbine is less. Hence the pressure of the discharged air will beincreased due to the increased speed of the impeller. This increase ofspeed ordinarily continues until the increasing pressure of the airovercomes the resistance to its passage. If, however,

the resistance is not overcome when a predetermined pressure is producedthe governor will become active at some corresponding predeterminedabnormal speed and prevent further increase of speed and pressure. p

The governor may be made to act in the manner above described in avariety of ways. As an example, one or more stops may be .provided whichhold the weights out away from the shaft axis and in such a positi onthat they are inoperative, in so far as their effect on the controllingvalve is concerned, until the speed of the bucket wheelexceeds thepredetermined limit after which they move the controlling valve towardits seat in the usual way until a balance is again effected between thesteam input and the output of compressed air. This relation continuesuntil the choke in the cupola is removed and the normal amount'of air isdischarged by the compressor, when the governor weights return to theirusual position against the stop or stops. Itnwill be seen that thegovernor has no control so longas the speed does not rise above saidpredetermined value, the full steam admission satisfying 'the ordinaryoperating requirements of the compressor, but it has control when theconditions beyond the compressor become abnormal to the extentdescribed. I

- A main valve may be provided in the steam supply pipe of the turbineto reduce the initial pressure whereby the normal operating conditionsof the apparatus may be changed and this without modifying theconstruction or relation of the arts.

In the accompanying drawings which illustrate one of the embodiments ofmy invention, Figure 1 shows a turbine-driven centrifugal compressorconnected to a eupola; and Fig. 2 is a view of the turbine with certainparts broken away.

1 indicates a centrifugal compressor which is designed to givepractically constant pressure for a given speed atall loads orquantities of air'delivered and is operated at. different speeds andpressures under the conditions above described. It is providedwith aninlet 2 through which air is supplied to the interior. of the compressorcase mg from any desirable source and with an outlet 3 which isconnected by a conduit 4 with a cupola or other apparatus 5 designedtoreceive air. Mounted on the mainshaft 6 is an impeller 7 of anysuitable construction which in the form illustrated in the drawingreceives through the openings 7 adjacent the shaft 6 an delivered to theinterior of the'casing by the inlet 2. Surrounding the impeller is anannulus 8 containing vanes 9 which convert the velocity of the airdischarged by the impeller into pressure before discharging it into theoutlet. The shaft is supported by bearings 10 and 11 of suitableconstruction. Mounted on one-end of the main shaft for driving it is aturbine bucket wheel 12, Fig. 2. The

turbine is provided with a casing 13 that is .15 or other device fordischarging fluid to the wheel buckets. Situated in front of the valvechest 16 is a second valve chest 18 containing an emergency valve 19which shuts off the steam supply in case of an emergency such as anexcessive and dangerous increase of speed due to the failure of the maingovernor to operate. This valve 19 may be actuated by any well knownform of emergency governing device which is brought into activeoperation by a certain speed greater than that normally permitted by themain governor. Steam is admitted to the chest 18 by aconduit 20containing a manually operated throttle valve 21. On the end of the mainshaft 6 is a centrifugal governor comprising weight-arms 22 whosemovements are opposed by the coiled extension spring 23. The tension onthis spring is such that it prevents the governor weights 30 from actingso long as the speed of the motor is normal or below normal and thequantity and pressure of the'air delivered by the compressor are normal.Said spring. also opposes the action of the weights during the increasein speed and pressure permitted when a choke occurs but its oppositionis overcome by the centrifugal action of the weights, when said speedand pressure reach the predetermined limit. The governor then holds thespeed substantially constant at that limit. One end of the spring 23 isthreaded to a fixed nut that surrounds said end while'the. opposite endis secured to a movable abutment 24. This abutment is connected by a rodwith one end ofa bell-crank lever 26 that is pivotally mounted withinthe casin 27. The other end of the lever is connected to the stem 28 ofthe valve 17.; Located at any suitable point, as for exam 1e, on theoutside of the shell surroun ing the spring and in line with the weights30, are stops 29 whlch limit the inward movement of the weights. Thesegovernor weights are in engagement with.

the stops for all speeds below that for which the governor is set, sothat the valve 17 remains wide open, this being the ordinary sultingincrease in the pressure of the air delivered by the compressor. Thisincrease continues until the pressure is sufficient to overcome thechoke or obstruction in the cupola when the load on the compressorreturns to normal, accompanied by a decrease in the speed of theturbine. Assuming, however, that the choke or obstruction in the cupolais not readily overcome, the speed of the turbine will increase to apoint where the governor becomes effective and prevents said speedbecoming abnormally great by decreasing the admission of steam. It willbe seen that under ordinary conditions the turbine is running with fullsteam admission and for all practical purposes without the governor, thespeed and pressure varying somewhat with the load, that is, with thequantity of air discharged ,by the compressor. This action continuesuntil the counter pressure and speed rise to a predetermined amount whenthe governor comes into service and maintains a constant speed anddischarge pressure of the compressor.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof;but I desire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out by other means.Vhat I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. In combination, a centrifugal compressor which delivers fluid atsubstantially constant pressure when driven at constant speed undernormal delivery conditions, a fluid-actuated motor for driving thecompressor, a regulating valve for the motor that is open to a fixedextent during the ordinary operation of the compressor and supplies aconstant quantity of motive fluid to drive the compressor at a constantspeed under normal delivery conditions and at an increasmg speed fromnormal speed up to a redetermmed limit above normal if the de ivery ofthe compressor is choked, and agovernor having a member that tends tohold the valve open and means responsive to said predetermined s eedthat overcomes the action of said mem er and closes the valve to agreater or less extent when the speed tends to exceed said limit.

2. In combination, a centrifugal air compressor which delivers air atapproximately constant pressure and volume so long as its outlet isunobstructed, a motor which is ungoverned during the ordinary operationof the compressor and is direct-connected to said compressor, meansdelivering a substantially constant supply of energy to the motor sothat its speed increases as the load decreases below normal, and a speedgovernor which is ordinarily inactive and only comes into service tolimit the speed of the motor by controlling the input of ener when thevolume of fluid delivered by-t e compressor decreases below apredetermined amount and its pressure increases to a predetermined limitdue to an obstruction in the compressor outlet. i

3. In combination, a motor which is connected to a centrifugal aircompressor which delivers air at approximately constant pressure atconstant speed and at higher'pressures at higher speeds, meansfurnishing a constant supply of energy to the motor during the ordinaryoperation of the compres- 10o sor and up to a predetermined increase inspeed and delivery pressure, and a speed governor which is ordinarilyinactive but becomes active at said predetermined speed to regulate thesupply of energy to the mo- 105 tor and prevent a further increase inspeed and delivery pressure.

4. In combination, a centrifugal compressor, a fluid-actuated motor fordriving it, a valve controlling the supply of fluid to the 110 motor,and means for holding the valve open to afixed extent while the load isnormal and during the decrease of the load to a certain point, saidmeans including speed responsive mechanism that becomes active at 11 aspeed corresponding to said point of decreased load and closes the valveto a greater or less extent.

5. In combination, a motor for driving a centrifugal air compressor,means furnish- 120 ing a substantially constant supply of energy to themotor during the ordinary operation of the compressor so that its speedincreases above normal as the load decreases below normal, and a speedresponsive mecha- 125 nism which is ordinarily inactive but becomesactive at a predetermined increase in speed above normal to regulate thesupply of energy to the motor to prevent a further increase in speed.

' 6. The method of operating motor-driven determined limit so as toprevent a further 10' Centrifugal compressors which consists infurnishing a substantially constant supply of energy to the motor duringthe ordinary operation of the compressor at normal load and .also as theload decreases so that the speed can increase with a decrease in load,and regulat-in .the supply of energy to the motor when t e speedincreases to a preincrease in speed.

In witness whereof, I have hereunto set my hand this second day ofMarch, 1908.

JOHN A; MCMANUB, Jr., 7 HENRY O. WEs'rENnAnr.

